In order to set up and provide a fast and convenient information transmission environment, people have been constantly developing and upgrading existing wireless networks (for example, mobile communication networks). In an orthogonal frequency-division multiplexing (OFDM) long term evolution (LTE) system, a carrier resource of no more than 20M is allocated to each user equipment (UE, also referred to as user device). However, to achieve a greater transmission bandwidth, 2 or more component carriers (CC) are aggregated. For example, carrier aggregation (including contiguous carrier aggregation and interband and intraband non-contiguous carrier aggregation) is supported in a LTE-advanced system to achieve a maximum aggregatable bandwidth of up to 100 MHz. Thus, 1-5 CCs may be allocated to a specific UE, and accordingly, resources used or collected by the UE may be distributed on these 1-5 CCs.
In a wireless network system (for example, a mobile communication network system), a base station (BS) is usually served as the access point of many wireless communication devices. Herein a wireless communication device may be a mobile station (MS, for example, a cell phone) or a user device (for example, a notebook computer). However, the MS may also be a user device and vice versa. A wireless communication device may be an immobile device (for example, a personal computer (PC)) or a mobile device (for example, a cell phone, a tablet PC, or any other mobile communication device).
Because each macro BS has a very large coverage area (also referred to as a macro coverage area) and supports a large number of wireless communication devices within its coverage area, each macro BS carries a heavy communication load. Besides, a macro BS is difficult to deploy due to environmental awareness and opposition. Additionally, because communication-starved spots may exist inside a building because of the deployed position of a BS or the shield of buildings or other objects, indoor communication quality may not be very satisfactory. Thus, the deployment of local or sub BSs (for example, pico BSs, femto BSs, and home BSs) has become a preferred solution for improving indoor communication performance.
A sub BS offers a low power, a great bandwidth, and a small sub coverage area therefore can improve the communication performance of any wireless communication device within its coverage area. However, because the coverage area of a macro BS and the coverage area of a sub BS often overlap each other, data transmitted within these two areas may interfere with each other. Moreover, the transmission performance of a macro BS may be affected by such interference or any issue regarding transmission resource allocation.